The Impact of Variability on Soft Real-Time System Scheduling

Executive Summary

Soft real-time systems sometimes operate under uncertain and unpredictable environmental conditions which makes event arrival times unreliable and variable. Input to such systems also change from time to time making event processing times variable. Due to such variations, traditional techniques using worst case times to estimate system performance deviate far from actual expected behavior. It would be more accurate to analyze such systems by considering the variance present in the system. More realistic performance prediction will help in decision making while deploying a system on to given hardware. This paper presents a Method of Stages based Analysis of soft Real Time systems (MoSART). MoSART takes into account variance in both the arrival and execution time and can model the performance of different scheduling algorithms.